OptionMonster's real-time systemsshowed 5,327 calls trading at the May 25 strike, which has averaged a mere 26 a day for the last month. Previous open interest at the strike was just 492 contracts, and most of the calls changed hands in a strong buying pattern for $0.40 to $0.55.

ASF closed yesterday down 3.21 percent to $22.34 and fell another 3.47 percent in after-hours trading. The stock has climbed steadily back from early February, when it plummeted some 27 percent after the last earnings announcement, and traders apparently believe that it will return to early 2010 levels above $24.

Administaff's stock would need to gain roughly 14 percent for the May 25 calls to turn a profit.